Repeat 2D array index tuples according to value in index

Question

I have a numpy 2D matrix and each cell may containing an integer value. for example:

[[0, 1, 0, 2, 3], 
 [2, 0, 1, 1, 1]]

I want to make a list that containing each (x,y) of cell times it's value, for example I want below list for above matrix:

[(1,0) , (3,0) , (3,0) , (4,0) , (4,0) , (4,0) , (0,1) , (0,1) , (2,1) , (3,1) , (4,1)]

In other words, the value of [0,1] is 1 so this x,y append in list "1" time.

I write this code. but it's really slow. How can I do this with an optimized method?

def page_to_std(data):
        h, w = data.shape
        res = []

        for y in range(0, h):
            for x in range(0, w):
                   amount = int(data[y][x])
                   for i in range(0, amount):
                      res.append((x,y))
        
        return res

Answer 1

It seems as though you're getting both axes mixed there. Assuming that is so, you can generate the index tuples with np.ndindex , and use np.repeat to repeat the resulting array of tuples according to the flattened input array:

coo = np.fromiter(np.ndindex(a.shape), dtype='i,i')
np.repeat(coo, a.ravel()).tolist()
# [(0, 1), (0, 3), (0, 3), (0, 4), (0, 4), (0, 4), (1, 0), (1, 0), (1, 2), (1, 3), (1, 4)]